However, the currency’s volatility is a concern for many regulators and potential investors. In a note yesterday Steven Englander, Citi’s head of G10 strategy, wrote that he is trying but “struggling” to find a way to analyze Bitcoin and is unsure it can be viewed as a currency. While Bitcoin has a robust supply control — there can never be more than 21 million Bitcoins in existence — Englander points out, “the difficulty is that a clever chap can go out and create ‘Nitcoin’ with similar increasing costs of production and finite supply, and someone else can create ‘Gitcoin.’” He also notes the volatility suggests speculation is a main price driver.